You may directly weld the sockolet to the pipe with Inconel filler, in which case you need not have overlay procedure. All you need is a procedure between Inconel plate or product with CS using Inconel filler.
If the connection is set on type then you have a problem. What would happen to the CS Edge (Assuming that the Inconel Component has Groove and Just a hole is cut on CS Pipe), you may have to cover this area with inconel weld (Which has undiluted chemistry of Inconel) this acts as Overlay, then in this case you have to support your WPS with over lay procedure coupon test (Not production coupon).
If you are going to do build up on CS (Buttering As in UW 42) you need not have overlay procedure.
If however you are doing clad metal restoration (Overlay) on the inside for the purpose of Corrosion protection then you have to have PQT Coupon tested for Side bend and undiluted chemistry check.
Some smart joint configuration may give you an escape route from Overlay procedure, in which case you may have to have Inconel to Inconel Procedure and Inconel to CS procedure. Check your drawing and with your designer.
If you are going to give build up in the CS weld edge and subsequently prepare the edge and put the sockolet and perform groove weld, then also Overlay PQT MAY not be required
But if you choose to perform PWHT after deposition of Inconel in the Carbon steel edge and subsequently weld the branch (Inconel) to Inconel weld then the situation becomes murkier. Then in such case One to one qualification would be necessary.
Now for some guess work, are you with some site piping contractor, if yuo are a manufacturer you have to have Overlay procedure since you are dealing with overlayed pipes. In any case Good Luck.
Too much of detail always leads to confusion. I have done my bit!
Good Luck